/usr
    mark
        book
            ch1.r
            ch2.r
            ch3.r
        course
            cop3530
                fall05
                    syl.r
                spr06
                    syl.r
                sum06
                    syl.r
        junk
    alex
        junk
    bill
        work
        course
            cop3212
                fall05
                    grades
                    prog1.r
                    prog2.r
                fall06
                    prog2.r
                    prog1.r
                    grades
